The upper house of Pakistan's parliament has backed a bill amending an Islamic law on rape and adultery.

Until now rape cases have been dealt with in Sharia courts. Victims had to have four male witnesses to the crime - or else face prosecution for adultery.

The new law, which must be approved by Pakistani leader Gen Pervez Musharraf, allows civil courts to try rape cases.

The senate rejected objections to the bill put forward by Islamist MPs who boycotted last week's lower house vote.

Khurshid Ahmed, a leader of an opposition coalition of religious parties, described the bill as "an attempt to promote an alien culture and secularism in Pakistan", according to the Associated Press news agency.

The new law allows for DNA and other scientific evidence to be used in prosecuting rape cases.

It also drops the death penalty for people having sex outside marriage.

A woman is raped every two hours and gang-raped every eight hours in Pakistan, according to the country's independent Human Rights Commission.

Correspondents say these figures are probably an under-estimation as many rapes are not reported.

Campaigners have said Pakistan's existing laws make it virtually impossible to prosecute rape.